Cylinder roller bearings with several rows are known in prior art. For example they are used in larger vehicle transmissions, in drives of machinery, or in machine tools, such as support rollers in mills, in which the roller bearings are subject to high radial and, if applicable, also axial loads and/or high rotation. In such bearings two or more rows of roller bodies are arranged between an external ring and an internal ring, which may be embodied with or without ledges for fastening and guiding the rows of bearings. The cylinder rollers are usually received and held spaced apart in cages with comb-like webs projecting from a central part unilaterally or at both sides in the axial direction. Depending on the bearing design and the number of rows of bearings, a cage arrangement may also be embodied as single or double roller cages, if applicable also as a combination of several such cages. Frequently, double-row cylinder roller bearings are provided with a roller-guided double web cage made from brass.
DE 29 22 361 A1 shows a double-row cylinder roller bearing with an external ring and an internal ring, between which two window cages are arranged, one cage for each row of bearings. The cages respectively comprise an axially external comb part with webs and an axially internal cap part with centering cams. During assembly first the two cap parts are placed onto a double sided internal ledge of the internal ring provided with webs at all sides to guide and fasten the roller bodies. Subsequently the rollers of both rows of bearings are filled in as well as arranged with the help of centering cams at a required distance. Subsequently the web parts are inserted axially from the outside between the rollers. In the assembled state the two window cages form a two-part symmetric double web cage.
DE 600 21 830 T2 discloses a one-part double web cage for a double-row cylinder roller bearing, in which webs axially project from a central ring part at both sides, off-set in reference to each other. In order to reduce the risk of tears and breaks, particularly at the connection sites between the webs and the ring part, which can develop by high bending stress due to radially transferred vibrations or abrupt acceleration and braking of the roller bearing, the cage construction is designed such that it fulfills certain bending specifications. Accordingly, the bending stress of the webs and the ring part shall be approximately equivalent. The cage is embodied geometrically identical at both rows of bearings.
JP 2001 208 075 A also shows a double web cage for a double-row cylinder roller bearing. The ring part and the webs show bore holes, with the bore holes in the webs being identical for both rows of bearings.
DE 10 2008 060 320 A1 shows another double web cage. In this cage the webs are enlarged at their radially inside base, starting from the outside towards the inside to a ring part. This yields an increased stability of the cage and particularly the risk for the web bases breaking is reduced during assembly and operation. The enlargements of the webs are embodied identically at both rows of bearings.
All of the above-mentioned double roller cages show a symmetrical web design between the two rows of bearings. Sometimes the assembly of double cylinder roller bearings with a unilateral double web cage in an efficient production process and during installation into the respective application seems relatively difficult, though, with regards to the assembly of the roller bodies. In particular in metallic double roller cages made from brass, for example, with exterior ledges for guiding and fastening the rows of bearings, the equipping of the bearing with the roller bodies occurs frequently axially and radially. In a first step the cylinder rolls of a first row of bearings are axially pushed into the cage, with for this purpose the cage being positioned axially offset in a bearing ring and the rollers are then inserted via an external ledge axially into the receiving pockets. Due to the fact that the cage is axially fixed by the assembly of the first row of bearings, the rollers of the second row of bearings cannot be inserted via the external ledge of the bearing ring but only from the top, i.e. inserted into the cage pockets in the radial direction. For this purpose, the webs of the second row of bearings can be appropriately narrowed in the circumferential direction such that the radial roller assembly is possible and simultaneously guidance and the secure fastening against falling out after the assembly are given.
From the consequently differently wide webs of the two rows of bearings an asymmetrical mass distribution results in the roller bearing which may lead to unfavorable kinematic features of the cylinder roller bearing. In particular, during operation with increasing rotations the roller bearing may tend to an asymmetrical and/or tilted positioning of the double roller cage, which may result in the running performance of the roller bodies being seriously disturbed.
In light of this background a cylinder roller bearing is known from JP 8 184 319 A with a double roller cage shows an asymmetrical mass distribution of two rows of bearings, in which an embodiment for facilitated assembly is provided. The cylinder roller bearing comprises an internal ring without a ledge and an external ring with external ledges and a central ledge. An axially aligned assembly groove is formed at one of the two external ledges for the axial insertion of the rollers of the corresponding row of bearings. The external ends of the webs of this row extend in a tapered fashion, being diagonally cut at one side radially inwardly. This way the receiving pockets are expanded such that the rollers can be inserted in a relatively easy fashion axially from the outside in an angular assembly position via the external ledge into the receiving pockets. Although the webs are not narrowed at this cage side to allow being equipped from the top; however, by the diagonal shape of the webs of one row of bearings and the assembly groove on this cage side an asymmetric mass distribution is given with the above-described negative consequences.